Automatic transmissions are used in a variety of vehicles. Automatic transmissions generally reduce the burden on a driver by automatically shifting the vehicle to a new gear based on conditions in the transmission. FIG. 1 depicts a conventional method 10 used by an automatic transmission. The load on the automatic transmission is monitored, via step 12. Thus, the condition of the automatic transmission is known throughout use of the vehicle. It is determined whether the load indicates that the shift thresholds of the automatic transmission have been reached via step 14. If the shift thresholds have not been reached, then no action is taken and the loads on the automatic transmission are continued to be monitored. If, however, it is determined that the shift thresholds have been reached, then the automatic transmission shifts, via step 16. If it is determined in step 14 that a lower shift threshold is reached, then the automatic transmission shifts to a lower gear in step 16. If it is determined in step 14 that a higher shift threshold has been reached, then the automatic transmission shifts to a higher gear in step 16. Thus, the automatic transmission shifts gears for the vehicle based on the load to the transmission.
Recently, global positioning satellite (GPS) systems have become more widely used in vehicles such as automobiles. A GPS system utilizes an orbiting GPS satellite and a GPS unit on the vehicle. Through communication between the GPS unit and the GPS satellite, the location, direction of travel and, in some cases, the altitude of the vehicle in which the GPS unit resides can be determined. Furthermore, the GPS system can be utilized to adjust the shift threshold of the automatic transmission. For example, GPS navigation systems ace typically equipped with a map indicating physical bodies, such as streets and buildings, in the area in which the vehicle currently is. This ability can be used to adjust the shift thresholds.
FIG. 2 depicts a conventional method 50 for changing operation of the automatic transmission using the GPS system. Based on GPS data obtained from the GPS navigation system, it is determined whether the vehicle is approaching some particular geographic body, via step 52. For example, the geographic body may be an intersection or a particular stretch of road. The particular type of geographic bodies are typically preset in the GPS system. The shift thresholds are then adjusted, via step 54. Thus, the shifting of the automatic transmission can be changed using the GPS system.
Although the conventional method 50 can improve performance of the automatic transmission, one of ordinary skill in the art will readily realize that the conventional method 50 is rather inflexible. In particular, the conventional method 50 utilizes only preset types of geographic landmarks to improve performance of the automatic transmission. Thus, other factors including but not limited to the behavior of the transmission are not accounted for. Thus, in general the shift thresholds for an automatic transmission are still relatively static. As a result, the automatic transmission may still shift at a non-optimal time given the local terrain. For example, the automatic transmission may still shift down just as a vehicle crests a hill or shift up just as the vehicle reaches a hill. The automatic transmission will then shift back up or back down shortly after the previous shift was completed. As a result, the smoothness of the ride, gas mileage, and the lifetime of the automatic transmission can be adversely impacted.
Accordingly, what is needed is a system and method for improving the performance and lifetime of the automatic transmission. The present invention addresses such a need.